The present invention relates to heat-laminable and high-gloss multi-layer films, oriented at least monoaxially, with a heat-laminable layer for the production of a composite with various substrates, such as e.g. paper, cardboard, pasteboard articles, metal foils, plastic films, cloth webs, fabric nets.
Multi-layer films of polyolefins possessing a stretched polypropylene layer and coated with various substances capable of hot melt adhesion, e.g. polyethylene, ethylene vinyl acetate or ionomers, are known e.g. from the Japanese published patent applications 60-109 834, 53-4082, U.S. Pat. No. 4,629,657 and EP-A-0 263 882. The known multi-layer films have various disadvantages, e.g. lack of interlayer adhesion, tendency of the laminated product to roll and, in particular, unsatisfactory optical properties. A further disadvantage is the tendency of the film to block on the roll, which has a negative effect on processability. EP 0 424 761 B1 describes a film with good interlayer adhesion and low tendency to block, but the optical properties of this film do not meet current requirements.
The object of the invention was to provide heat-laminable multi-layer films which do not have the disadvantages listed, in particular the unsatisfactory optical properties and the tendency to block on the roll, and are therefore suitable as laminating films, especially for high-gloss lamination.
Surprisingly, this was achieved by providing a film of the type mentioned at the beginning oriented at least monoaxially, which is characterised in that it contains a base layer I, which comprises polypropylene, an external layer II, which also comprises polypropylene, and an external layer III which can be heat-laminated by applying heat, characterised in that the layer III comprises an ethylene vinyl acetate copolymer A and an ethylene vinyl acetate copolymer B and these two ethylene vinyl acetate copolymers have different vinyl acetate contents